Hi,
spec:
Dont jump the gun just yet
Tony:
This brings up the question, what spec's are there in the original requirement? That really tells us how critical we have to be.
For example, we know from the general diode curve that when D3 is conducting D2 will not be conducting much at all, so that means the voltage drop across D3 will be higher than the drop across D2. The saturation voltage of the output transistor of the 555 is non zero. These two taken together means that the output will not reach exactly to zero when the output state is logically zero.
But does it have to go all the way to zero?
We also know that op amps do not respond as fast as we would like sometimes, but do we have an original spec that tells us what rise and fall times have to be met?
So it depends a lot on what we really need. I think it would be wrong to compare to a commercial unit unless we really were trying to duplicate that kind of device perfectly.
spec:
Dont jump the gun just yet
A spec without defining the source impedance and load impedance for each of multiple outputs is not a spec.
Nor is max load 50 Ohms a spec. nor is it a pulse with 1ns rise time.
If you model an ideal voltage source, load does not matter with tolerance.
But a true voltage source contradicts a 50 Ohm source with <1ns rise time.
Hence what spec!
Tony:
This brings up the question, what spec's are there in the original requirement? That really tells us how critical we have to be.
For example, we know from the general diode curve that when D3 is conducting D2 will not be conducting much at all, so that means the voltage drop across D3 will be higher than the drop across D2. The saturation voltage of the output transistor of the 555 is non zero. These two taken together means that the output will not reach exactly to zero when the output state is logically zero.
But does it have to go all the way to zero?
We also know that op amps do not respond as fast as we would like sometimes, but do we have an original spec that tells us what rise and fall times have to be met?
So it depends a lot on what we really need. I think it would be wrong to compare to a commercial unit unless we really were trying to duplicate that kind of device perfectly.